Add pixel saving feature

[maxso216]

From version 89, the appearance of firefox change, which make it look better, but make the browsing area/safe area smaller. The titile bar become larger, which consuming more pixel. A pixel saving option which shink title bar, removing unnecessary appearance, etc ,can make browsing area become larger.

#Desktop

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[jscher2000]

Firefox 89+ are hiding the Compact density mode because there was a plan to eventually phase it out. If you would like to experiment with it, the following support article will get you started:

https://support.mozilla.org/kb/compact-mode-workaround-firefox 

Of course, you might have other things you want to reduce that aren't covered by that feature.

[maxso216]

This is good, the compact density mode is very useful for me. It makes my browser look a lot nicer and tidy that fit in the OS style.